The fact that you were literally right in the middle of a war as it was happening somehow makes it even better.
Even though you saw it coming a mile away, Jansen marrying Ming during the ending put such a smile on your face.
Even earlier, at the scene just after the large fight in Numara, with Ming confessing her love on the shipdeck. One line seals it: "I'm so glad I met you."
Kaim has one of these in the TYoD story Signpost.
Whenever the music piece 'A Sign of Hope' starts playing in the Thousand Years of Dreams.
Crosses with Tear Jerker, but in the Old Sorceress's Mansion, you meet the Old Sorceress, who is begging to sleep and be alone. Realizing who it actually is: Sarah, distraught over Lirum's death, Cooke and Mack sing a lullaby to bring her back to her senses.